Plug receiving contact



Dec. 14, 1965 K. M. HAMMELL 3,223,962

PLUG RECEIVING CONTACT Original Filed 001;. 8, 1956 INVENTOR.

lflemper M. Hqmme United States Patent Office 3,223,962 PLUG REKJEIVINGCONTACT IIernper M. Hammell, Harrisburg, Pa, assignor to AMPIncorporated, Harrisburg, Pa. Continuation of application Ser. No.614,551, Oct. 8, 1956. This application Sept. 30, 1963, Ser. No. 313,4143 Ciairns. (Cl. 339-256) This application is a continuation of mycopending application, Serial No. 614,551, filed October 8, 1956, andnow abandoned. This invention relates to disconnect electricalterminations of the so-called friction type and more particularly to apin receptacle connector.

In many applications it is desirable to terminate wire leads from anapparatus in a group of pins or posts which are adapted to befrictionally engaged in a female receptacle connected to suitable cablesfor connection to the rest of the electrical circuit. Typicalapplications for connections of this type are in the refrigerating andair conditioning fields where portions of the equipment are hermeticallysealed and connection must be made to a series of pins or postsextending through the shell of the hermetically sealed portion.

Heretofore various pin receptacle connectors have been suggested andhave been partially successful for certain limited application. Howeverunder severe operating conditions, both temperature and humidity, it hasbeen found that all connections heretofore known have failed to give thedesired low resistance contact over a long period of time necessitatingeither frequent cleaning or replacing of the connections. According tothe present invention I have discovered that by placing specialwrap-around pin contacting surfaces on a pair of parallel bridge-likeflexible spans that a greatly increased contact area of low unit contactpressure can be obtained resulting in a superior long life connection.

It is an object of the present invention to provide a pin receptaclehaving substantially more than a line or point contact with the pininserted therein. It is another object of the present invention toprovide a pin receptacle that has low unit contact pressure over a largearea of contact. It is another object of the present invention toprovide a low contact resistance pin receptacle that will maintain itslow resistance contact throughout a long period of time under adverseatmospheric and temperature conditions. It is another object of thepresent invention to provide a pin receptacle of improved low contactresistance that may be made of cheaper, more readily available materialsthan heretofore known. It is a still further object of the presentinvention to provide a pin receptacle with wrap-around contact surfacesto provide substantial areas of contact with a pin inserted therein.These and other further objects will be in part apparent and in partpointed out as the specification proceeds.

In the drawings:

FIGURE 1 is a side elevation of the pin recepticle of the presentinvention;

FIGURE 2 is a top plan view of the pin receptacle of the presentinvention;

FIGURE 3 is an end view of the pin receptacle of FIGURE 2;

FIGURE 4 is a fragmentary view of the contact portion of the pinreceptacle of FIGURES 1 through 3 priorto Patented Dec. 14, 1965insertion of a pin showing the relative curvature of the pin and contactsurfaces thereof;

FIGURE 5 is a view similar to FIGURE 4 showing the pin inserted in thepin receptacle.

Referring now to FIGURE 1 the pin receptacle 20 comprises generally thereceptacle portion 22, a barrel portion 24 and an insulation supportportion 26. The barrel portion 24 and insulation support portion 26 areof conventional design and crimped according to a wellknown crimp andare not described in detail herein for the sake of brevity. Thereceptacle portion 22 comprises generally two thin gauge spans 28 and 30which are supported at the top by the tabs 32 and 34 and at the bottomby the U-shaped root sections 36 and 33 respectively of the connector.Each of the spans 28 and 30 has an inwardly concave contact surface 40at approximately the center thereof and a pair of slots 42 cut thereinas will be described in detail herein.

As may be seen in FIGURES 1 through 3 the locking ears 32 and 34 areformed integrally with the spans 28 and 30 and then bent substantiallyat right angles thereto to engage the opposite span. FIGUURES 1 and 3show at the end of the ears 32 and 34 a locking tab 44 which extendsupwardly to engage the side of the opposite span. The locking ears 32and 34 as they are bent around to engage the opposite span seat in acut-out 46 which cooperates with the tabs 44 to provide the desiredsupport of the upper edges of spans 28 and 31 In addition to giving thesuperior performance as will be described herein in actual operation theforegoing constructure together with the root sections 36 and 38 allowan independent control of the width of both the top and bottom of thereceptacle portion 22 in the manufacture thereof which results inincreased flexibility of the product and better quality control in themanufacturing thereof.

The spans 28 and 30 are formed of a relatively thin gauge stock so thatthey are somewhat flexible and act like bridge spans joined at the endbut free to flex in the middle. The contact areas 40 have a radiussomewhat greater than the radius of the pin to which they are to beconnected and are spaced apart somewhat less than the diameter of thepin to which the receptacle is to be joined. This may be seen in FIGURES4 and 5. Also the upper edge of the contact surfaces 40 are s-waged orotherwise beveled outwardly at 41 in somewhat the manner of a bell mouthto facilitate the entrance of the pin therein.

FIGURE 4 shows receptacle 20 in its normal position with a pin 48 aboutto enter into the receptacle portion thereof. As may be clearly seen thepin 48 is slightly larger in diameter than the spacing between thecontact surfaces 40 of the receptacle 20. However it will be noticedthat the radius of curvature of the contact surfaces themselves aregreater than the radius of curvature of pin 48. In FIGURE 5 the pin 48has been inserted into the receptacle 20 and as may be readily seen thishas sprung the spans 28 and 30 somewhat apart and in so doing has causedthem to wrap around the pin 48 to provide a relatively large area ofcontact between the contact areas 40 and the pin 48. This flexing hastaken place between the suspension points at the top and bottom of theends of the spans 28 and 30 as previously described. The flexing orbending actually takes place in the contact surface portions 40 insuringa complete and intimate wraparound contact over a substantially largerarea of the pin than heretofore possible.

Without the bending of the surfaces 40 contact is obtained along a linesuch as 43 in FIGURE 4. With the flexing taking place in surfaces 40 awide area of contact is obtained as between lines 45 and 47 in FIGURE 5.

Since the spans 28 and 30 are of relatively thin gauge metal thepressure necessary to produce this flexing is relatively slight and theactual contact pressure is of a low unit magnitude although the totalpressure holding the receptacle on the pin may be considerably greaterthan that encountered with other types of receptacles having single lineor point contacts but very high unit pressures. This not onlyfacilitates the connection and disconnection of the receptacle and pinbut also provides a greatly increased life and a much lower averagecontact resistance between the receptacle and the pin.

With the high unit pressure line or point contact type of receptacleoccasionally the initial contact obtained between the receptacle and pinmay be greater than that obtained with the receptacle of the presentinvention. However it has been conclusively found that such a connectionin the presence of high temperature and humidity very soon loses its lowinitial resistance and in a short period of time will have developed arelatively high contact resistance that progressively gets worse untilthe joint or connection fails. On the contrary with my broad area, lowunit contact pressure connection while the initial contact resistancemay be slightly greater than with other types of high unit pressurecontacts the resistance remains substantially constant and does notincrease materially under the influence of high temperature andhumidity.

For instance with the former type line contact, high unit pressureterminal, a terminal temperature of as high as 380 degrees Fahrenheit isnot uncommon in an ambient temperature of approximately 200 degreesFahrenheit. With my broad area, low unit contact pressure terminal themaximum temperature observed has been only 250 degrees Fahrenheit withan average somewhere in the neighborhood of 230 degrees Fahrenheit.Furthermore, the voltage loss in the connection has been measured atmore than 300 millivolts at 5 amperes load for the former, while with myconnection the average drop has been millivolts with a maximum ofbetween and 50 millivolts. It is obvious from this data that the minimumservice life of a connection according to the present invention would bemany times that of a connection of the line or point, high unit contactpressure type.

This low temperature of my receptacle has a further advantage in that itis possible to utilize cheaper materials since the temperaturerequirements are not as severe. For instance, in the example given aboveit is possible to use with my receptacle a Phosphor bronze materialwhich has very satisfactory creep stability at the 250 degree Fahrenheitmaximum temperature encountered, however, with the line contact type ofterminal a beryllium copper which is three to four times as expensive isnecessary if creep stability is to be maintained at the elevatedtemperature of 380 degrees Fahrenheit encountered with that type ofconnection.

Referring again to FIGURES 1 through 5 it will be noted that the spans28 and 30 are substantially parallel from top to bottom thereof and thatin actual application such as FIGURE 5 they are still substantiallyparallel from top to bottom. This, it has been found, is a veryimportant feature of my pin receptacle in that if the contact areas 40are not maintained substantially parallel when the pin 48 is insertedtherein it will cause a spreading out of the contact areas such thatonly a line or ring contact is established at the lower or upper end sothat only a very small area of contact will be obtained at either theupper or lower end of the contact surfaces 40. As described herein, byadjusting the locking ears 32 and 34 and the spans 36 and 38 during themanufacture of the receptacle the spans 28 and 30 will be maintainedvery closely parallel. In actual operation I have found that if thedistance between the tops of the spans 28 and 30 is not over twotothree-thousandths greater and not over four-thousandths less than thedistance at the bottom that uniform low resistance contact throughoutthe entire length of the contact area 40 will be obtained.

Referring now to FIGURE 1 a cut-out will be seen at the bottom of thereceptacle 20. This is provided to ensure the resilient bridge spanaction of the spans 28 and 30. The slots 42 help in the accurate formingof contact surfaces 40 and under certain conditions help to reduce thefrictional drag where ease of application is of paramount consideration.

While there is given above certain specific examples of this inventionand its application in practical use, it should be understood that thisis not intended to be exhaustive or to be limiting of the invention. Onthe contrary, these illustrations and explanations herein are given inorder to acquaint others skilled in the arts with this invention and theprinciples thereof and a suitable manner of its application in practicaluse, so that others skilled in the art may be enabled to modify theinvention and to adapt and apply it in numerous forms each as may bebest suited to the requirement of a particular use.

I claim:

1. An electrical connector for detachably securing together electricalconductors by frictional contact between a pin contact and a pinreceptacle comprising in combination a barrel portion for pressureforming about the end of an electrical conductor, a pin receptacleportion including a pair of parallel span members integrally joinedtogether at opposite ends of one side, a pair of locking ears mounted onthe ends of said spans adjacent the unjoined sides thereof, acooperating locking slot adapted to receive therein said locking ears tosecurely hold the other side of said spans in proper spaced relation, aninwardly concave contact surface formed in said spans adjacent themid-point thereof, a narrow slot in said spans on each side of saidcontact surfaces, said spans being spaced apart a distance such thatsaid contact surfaces are spaced less than the diameter of the pin to bereceived therein and said surfaces having a radius of curvature greaterthan said pins.

2. Al one-piece resilient sheet metal receptacle for slidably receivingan elongated contact member in detachable frictional engagement toeffect an electrical connection comprising a pair of opposed elongatedcontact surfaces spatially disposed less than the correspondingdimension of the contact member and defining a socket for axialreception of the contact member, side wall portions extending laterallyfrom opposed sides of each of said surfaces at both ends of said socket,a pair of spaced bights and ear means extending from and rigidilyanchoring the end portions of said sidewall portions, said bights beingon opposite sides of said socket at one end thereof, said ear meansextending from one side and interlocking with a sidewall portion on theother side of the socket at the other end thereof, said bights and earmeans being substantially in transverse alignment with the lateralextent of said sidewall portions, so that said sidewall portions andintermediate portions of said contact surfaces are constrained to flexas resilient beams fixed at both ends.

3. A one-piece resilient sheet metal receptacle for slidably receivingan elongated contact member in detachable friction engagement to effectan electrical connection comprising a pair of opposed elongated contactsurfaces spatially disposed less than the corresponding dimension of thecontact member and defining a socket for axial reception of the contactmember, sidewall portions extending laterally from opposed sides of eachof said surfaces at both ends of said socket, bight means extending fromand rigidly anchoring the end portions of said sidewall portions at oneend of said socket, ear means extending from and rigidly anchoring theend portions of said sidewall portions at the other end of said socket,

both ends.

5 6 said ear means extending from one side and interlocking 2,502,385 3/1950 Ludwig 339-208 with a sidewall portion on the other side of thesocket, 2,519,584 8/1950 Ludwig 339208 said bight means and ear meansbeing substantially in 2,600,190 6/1952 Batcheller 339256 transversealignment with the lateral extent of the asso- 2,663,457 12/ 1953Shaffer. ciated ones of said sidewall portions so that said sidewall 52,711,524 6/ 1955 Beaver 339-256 portions and intermediate portions ofsaid contact sur- 2,720,636 10/1955 McKinley 339-192 faces areconstrained to flex as resilient beams fixed at 2,728,060 12/1955 Doeg339-192 FOREIGN PATENTS References Cited by the Examiner 10 408,301 4/1934 Great Britain. 604,880 7/ 1948 Great.Britain. UNITED STATES PATENTS640,432 7/1950 Great Britain.

4/ 1902 Betts. 1/1332 g 3 ALBERT H. KAMPE, Primary Examiner.

ar or 10/1938 Baker 5 JOSEPH D. SEERS, PATRICK A. CLIFFOgD, 12/1941Clayton. mmmers-

1. AN ELECTRICAL CONNECTOR FOR DETACHABLY SECURING TOGETHER ELECTRICALCONDUCTORS BY FRICTIONAL CONTACT BETWEEN A PIN CONTACT AND A PINRECEPTACLE COMPRISING IN COMBINATION A BARREL PORTION FOR PRESSUREFORMING ABOUT THE END OF AN ELECTRICAL CONDUCTOR, A PIN RECEPTACLEPORTION INCLUDING A PAIR OF PARALLEL SPAN MEMBERS INTEGRALLY JOINEDTOGETHER AT OPPOSITE ENDS OF ONE SIDE, A PAIR OF LOCKING EARS MOUNTED ONTHE ENDS OF SAID SPANS ADJACENT THE UNJOINED SIDES THEREOF, ACOOPERATING LOCKING SLOT ADAPTED TO RECEIVE THEREIN SAID LOCKING EARS TOSECURELY HOLD THE OTHER SIDE OF SAID SPANS IN PROPER SPACED RELATION, ANINWARDLY CONCAVE CONTACT SURFACE FORMED IN SAID SPANS ADJACENTS THEMID-POINT THEREOF, A NARROW SLOT IN SAID SPANS ON EACH SIDE OF SAIDCONTACT SURFACESE, SAID SPANS BEING SPACED APART A DISTANCE SUCH THATSAID CONTACT SURFACES ARE SPACED LESS THAN THE DIAMETER OF THE PIN TO BERECEIVED THEREIN AND SAID SURFACES HAVING A RADIUS OF CURVATURE GREATERTHAN SAID PINS.